Process for hardening protein layers

ABSTRACT

A process for hardening photographic gelatin layers, wherein a dihalogen substituted di- or triazine is added as hardening agent to the casting solution for the photographic layer; the casting solution is applied onto the support and the layer is dried. The drying the performed in effective contact with a water-soluble salt of a primary, secondary or tertiary amine.

Unite Etates Patent Mucke et a1. Feb. 29, 1972 [54] PROCESS FOR HARDENING PROTEIN [56] References Cited LAYERS UNlTED STATES PATENTS [72] Inventors: Bruno Mucke, Koeln-Buchheim; Karl Lohmer, Level-lumen; Heinrich Gold 3,288,775 1 1/1966 Anderau et all ..96/1 I 1 X Koeln Stammhim, n f Germany 3,325,287 6/1967 Yamamoto et al. ..96/ 1 1 1 [73] Assignee: Agfa-Gevaert Aktiengesellscha ft, Lever- Primary Examiner Norman Torchin kusen Germany Assistant ExaminerRichard E. Fichter [22] Filed: Aug. 8, 1969 Attorney-Connolly and Hutz 211 Appl. No; 848,717 [57] ABSTRACT A process for hardening photographic gelatin layers, wherein [30] Fomgn Apphcauon Pmmty Data a dihalogen substituted dior triazine is added as hardening Aug. 27, 1968 Germany ..P 17 95 237.3 agent to the casting solution for the photographic layer; the casting solution is applied onto the support and the layer is 260/117 dried. The drying the performed in efi'ective contact with a [5 l Int. Cl ..G03C 1/30 wate usoluble alt of a primary, econdary or tertiary amine, [58] Field of Search ..96/111;260/117; 106/125 5 Claims, No Drawings PROCESS FOR HARDENING PROTEIN LAYERS The invention relates to a process for hardening protein layers, particularly gelatin layers, and in particular photographic layers, using halogen-substituted, nitrogen-containing heterocyclic compounds as hardeners and amines as hardening accelerators.

It is known to harden protein layers, particularly photographic gelatin layers, so that the mechanical properties and stability to heat and moisture of the layers are improved. Many different types of compounds have been ,used as hardeners, e.g. aldehydes, acid halides, epoxides, ketenes, compounds which have several double bonds or cyclic compounds with substituents which are active as hardeners.

However, these known hardeners only inadequately meet the high standard which are required, especially in photographic practice. The hardening reaction generally proceeds too slowly. Complete hardening is achieved only after weeks or months. Although the rate of hardening can be increased by increasing the concentration of the hardener, this in most cases impairs the photographic properties, e.g. the sensitivity, gamma or tone of the silver image.

It also known to accelerate the hardening reaction by other means. When compounds are used, the hardening effect of which depends on the pH, for example, this can be achieved by changing the pH. The addition of volatile amines before drying the photographic layers has been described for this purpose. The pl-l of the layer is thus increased to about 8 to 9 during drying. The volatile amines evaporate during drying so that the photographic material actually supplied for use then has a pH in the usual range of about to 7.

Additives which accelerate the hardening reaction have not so far become known for other known hardeners in which the action is not dependent upon the pH, e.g. halogen-substituted dior tri-azine compounds which have extremely advantageous photographic properties.

It is among the objects of the invention to provide a process for hardening protein layers, in particular photographic gelatin layers, more particularly to provide hardening accelerators for known hardeners which have advantageous photographic properties.

We now have found a process for hardening protein layers, in particular photographic gelatin layers which contain as hardeners derivatives of dior tri-azines at least two ring carbon atoms of which are substituted with halogen, wherein the drying is performed in the presence of ammonium salts as hardening accelerators.

The dior tri-azine derivatives found to be suitable are usually di-substituted pyridazines, pyrimidines, pyrazines or symmetric or asymmetric triazines. 1,3,5-Triazines of the following formula have been found to be particularly useful:

I'Ialogen in which R is an alkyl group, preferably a short chain alkyl group having up to five carbon atoms, an alkoxy group, also preferably having up to five carbon atoms, alkoxy substituted alkoxy, both alkoxy groups having up to five carbon atoms, such as 2-methoxyethoxy or 2-ethoxyethoxy, an aryl group, in particular a phenyl group, an aralkyl group, e.g. a benzy'l or phenylethyl group, a phenoxy, aralkoxy such as benzyloxy or phenylethoxy, hydroxylamino, carboxyl or sulfonic acid group. The above substituents, in particular alkyl or phenyl groups, may carry additional substituents, e.g. halogen, hydroxyl, alkyl alkoxy etc.

Suitable halogens on the triazine ring are in particular fluorine and chlorine.

The water-soluble salts of primary, secondary and tertiary amines may be used as accelerators. The free amines may also be used as accelerators, provided they do not have any disadvantageous effect on the photographic emulsions, if the pH of the emulsion is maintained at the usual pH for photographic emulsions of 5 to 7 by the addition of acid. Under these conditions, the salts of the amines form in the emulsion. Aliphatic tertiary amines more preferably those which contain at least two nitrogen atoms are especially suitable.

The following are examples of suitable amines: tert.butylamine, morpholines, piperazines, pyridines, a, fi-or 'ypicolines, alkylation products, including e.g. methyl morpholines or methylpiperazines, triethylenediamines, dimethylanilines, quinolines, dimethylallylamines, dimethyl-fiethoxyethylamines, pentamethyldiethylenetriamines, hexamethyltriethylenetetramines, triethylenediamines, l,2-bisdimethylaminourethane, l,4-bis-dimethylaminobutane, 1,6- bis-dimethylaminohexanes, dimethylisopropylamines, dimethylpropylamines, trimethylamines, pyrollizidines, l-azabicyclo-(2,2,l )-heptane, quinuclidine, quinuclidone, l-azabicyclo-(3,2.l )-octane or l-aza-bicyclo-( 3,2,2)-nonane and in particular 1,4-diaza-bicyclo-(2,2,2)-octane.

The quantities of hardener or hardening accelerator which are added may vary within wide limits. The quantity required depends on the nature of the photographic layer and the required degree of hardening. The optimum quantities for any particular purpose can be easily determined by simple tests. As a general rule, if the finished layer has a gelatine application of 10 to 20 g. per m. between 30 and 100 mg. per m? of hardener, e.g. a triazine, and between 10 and 200 mg. per m3 of accelerator, preferably between 20 and mg. per m7, have been found to be sufficient.

According to a preferred embodiment, hardener and hardening accelerator are added to separate layers. For hardening photographic gelatine layers, the hardening accelerator is preferably added to the light-sensitive silver halide emulsion layer and the hardener to any adjacent auxiliary layer. Adverse influences of the hardener on the photographic properties of the emulsion during casting are eliminated by this method.

The hardening reaction then occurs during drying of the moist layers and is further accelerated by increasing the temperature during the drying process.

The process according to the invention yields layers which are completely hardened after only a few minutes and are no longer soluble after drying, even in hot water. Hardening has by that time already reached its final stage so that practically no change in the mechanical properties occurs during storage of the layers. This is of very great practical importance especially for photographic layers.

The process according to the invention differs fundamentally from the known processes in which hardening, effected by using other hardeners, is accelerated by increasing the pH. As already mentioned, the amines are present in the form of their salts and the hardening reaction proceeds at neutral to slightly acid pH values. The amines or their slats are not added in order to alter the pH and thereby achieve acceleration of the hardening reaction; on the contrary, the pH is kept constant. Under the conditions described here, the effect of the ammonium salts claimed of accelerating hardening is confined to the above halogen-substituted heterocyclic compounds. Thus, for example, when using triacryloylhexahydrotriazine as hardener, no acceleration of the hardening is found when using the method described. The reason for the accelerating effect of the ammonium salts in the process according to the invention has not been completely elucidated. Presumably, the effect is due to the intermediate formation of more highly active addition compounds.

EXAMPLE 1 15 ml. of a 10 percent solution of the hydrochloride of triethylenediamine and l g. of saponin are added to 1 kg. of a silver chlorobromide gelatine emulsion (0.24 mol of silver halide and g. of gelatine) and the emulsion is cast on barytacoated paper support, 70 g. of emulsion per m? being applied to the paper.

When the layer has solidified, another layer consisting of a 4.5 percent gelatine solution which contains 4 g. of 2-(2- methoxyethoxy)-4,6-dichloro-s-triazine is applied as protective layer.

After drying (drying time 45 minutes, drying temperature 40 C.), the layers are hardened.

A sample of this is exposed behind a step wedge and developed for 30 seconds at 35 C. in a conventional developer and then fixed and washed. After washing, the sample is immediately subjected to mechanical heat drying on a conventional high-gloss drum; no sign of melting is observed in the process.

The hardened layer is not affected even by 5 minutes boiling in water. The emulsion remains firmly bonded to the layer support.

Similar satisfactory results are obtained if the hardening accelerator is added to a layer which is arranged below the emulsion layer.

Equally good hardening is achieved when a transparent layer support, e.g. of cellulose acetate, or ofa polyester based on polyethylene terephthalate is used.

Other combinations of hardeners and hardening accelerators above-mentioned the above mentioned type, e.g. the following combinations, were tested in the same way and excellent results were obtained:

Hardener Hardening Accelerator 2-Benzyloxy-4,6-dichloro- Triethylenediamine s-lriazine hydrochloride 2-(a-methoxyethoxy)-4,6- N-methylmorpholine dichloro-s-triazine hydrochloride 2-lsopropoxy-4,o-dichloro- Triethylenediamine striazine hydrochloride EXAMPLE 2 g. of the yellow coupler 2-(4'-benzoylacetaminophenyl)- l-octadecylbenzimidazole-S-sulfonic acid and 1 g. of saponin as wetting agent and l g. of the hardening accelerator triethylene-diamine hydrochloride are added to a silver bromide gelatine emulsion which contains 0.2 mol of silver halide and 100 g. of gelatin per kg. The emulsion is applied onto a baryta-coated paper support so that the application of silver is 0.8 g. per m? ofsilver in the form of silver halide.

After solidification, a gelatine layer which contains 45 g. of gelatine, l g. of saponin and 2 g. of 2-(2-methoxyethoxy)-4,6- dichlorotriazine as hardener per kg. is cast on the light sensitive layer.

Over this is cast a green sensitized silver chloride gelatine emulsion which contains 0.21 mol of silver halide, 100 g. of gelatine and 1 g. of saponin as well as l g. of the hardening accelerator triethylenediamine hydrochloride and 23 g. of the magenta coupler of l-(4-phenoxy-3'-sulfonyl)-3-stearylpyrazolene-S per kg. The application per 111. is 0.6 g. of silver in the form of silver halide.

The same intermediate layer of gelatin as described above is placed on this green sensitive layer.

The uppermost layer applied is a silver chloride gelatine emulsion which has been sensitized for the red region of the spectrum and which contains 0.22 mol of silver halide, g. of gelatine, l g. of saponin, l g. of the hardening accelerator triethylenediamine hydrochloride and 18 g. of the cyan coupler l-octadecyl-2,2'-( l '-hydroxynaphthyl)-benzimidazole-5- sulphonic acid per kg.

The same gelatine layer that was used as separation layer between the other emulsions is cast on this as a protective layer.

After drying, a step wedge is exposed and the exposed strip is treated in an N,N-diethyl-p-phenylenediamine color-forming developer at 30 C. During this process, the material shows good resistance to damage of the layers. When processing is completed, the film can be dried mechanically without additional hardening.

We claim:

1. In a process for hardening photographic gelatin layers by applying onto a support, a casting solution for the said photographic gelatin layer containing a hardening agent having the formula N R-? (T -Halogen N N 5 Halogen in which R is an alkyl group, an alkoxy group, alkoxy substituted alkoxy, both alkoxy groups having up to five carbon atoms, a phenoxy, an aralkoxy, carboxyl or sulfonic acid group, and drying the layer, the improvement consisting of performing drying in effective contact with the water-soluble salt of a primary, secondary or tertiary amine in a quantity in the range of l0-200 mg. per/m. ofthe layer.

2. The process of claim 1, wherein drying is performed in the presence of water-soluble salts of aliphatic tertiary amines which have at least two nitrogen atoms.

3. The process of claim 1, wherein drying is performed in the presence of water-soluble salts of cyclic tertiary amines which have saturated rings.

4. The process of claim 2, wherein drying is performed in the presence of water-soluble salts of triethylenediamine or morpholine or derivatives thereof.

5. The process of claim 1, wherein the photographic gelatin layer contains color couplers. 

2. The process of claim 1, wherein drying is performed in the presence of water-soluble salts of aliphatic tertiary amines which have at least two nitrogen atoms.
 3. The process of claim 1, wherein drying is performed in the presence of water-soluble salts of cyclic tertiary amines which have saturated rings.
 4. The process of claim 2, wherein drying is performed in the presence of water-soluble salts of triethylenediamine or morpholine or derivatives thereof.
 5. The process of claim 1, wherein the photographic gelatin layer contains color couplers. 